# Tag Info

41

When the brakes are on, they apply a backwards force that counters the engine thrust. This force is applied at ground level, and the engine thrust is higher. These two forces result in a moment that forces the nose down, compressing the nose gear slightly. When the brakes are released, the moment disappears and the nose gear extends. Another factor here is ...

31

Surface 1 is a horizontal stabilizer with elevator, just the same as on any other aircraft with a T tail arrangement. Surface 2 is called a rear strake or a tail fin. There is one on each side of the fuselage. They provide extra stability during operation at high angles of attack when the fuselage is disturbing the airflow to the vertical tail. They are ...

19

All quotes in this answer are from the English translation of the BEA accident report. The elevator cable broke at "an altitude estimated at between three and four hundred feet",(p. 7) and there were eleven seconds between that time and the point of impact. If it had happened higher, the pilot would potentially have had time to figure out what happened and ...

18

The key thing missing in your interpretation is that the order is important. Applying the same roll, pitch and yaw angles in a different order will result in a different orientation (mathematically this is because rotation matrices do not commute). The correct order is: Yaw (for an airplane this is typically called the heading) Pitch Roll For any given ...

16

The driving variable here is airspeed, not pitch attitude per se. Your airplane naturally goes faster when you put the stick forward and decrease the wing's angle-of-attack, and this changes the prop rpm. Your pitch input is changing the wing's angle-of-attack which leads to an airspeed change. Even with the engine switched off, the aircraft would fly (...

14

What you ask is: If a model glider is thrown at a higher speed than its trim speed, why does it pitch up? Short answer: Because the rear horizontal surface produces less lift per area than the forward surface. When flying at a speed different from its trim speed, the combined center of lift of all surfaces is shifted such that it creates a pitching moment ...

14

Pitch is measured with respect to a plane orthogonal to the local weight¹ force, which is properly called the horizontal. That is used because: It is equipotential plane of the gravitational field. Moving around it won't change your potential energy. Is always well defined. Is smooth and locally flat (it is still a spherical surface globally, of course). ...

12

Generally, a slight nose-up attitude gives the best performance. This allows the fuselage to create some lift without producing too much drag, thus filling the drop in the spanwise lift distribution created by the interruption of the wing by the fuselage. However, in passenger aircraft this will make the job of attendants much harder because their trolleys ...

12

Look carefully and you can see the nose strut is compressed down to only a few inches of chrome as the thrust applies a torque moment, or nose down pitching moment, about the fixed axis of the main tire contact points with the runway. On brake release, the axis about which the torque is being applied, the rubber to runway interface, is also no longer fixed,...

11

Roll, pitch and yaw are rotations about the principle body axis of the aircraft. Roll angle, pitch angle and yaw angle together describe the attitude of an aircraft. The principle body axes are: X-axis is the longitudinal axis pointing out the nose of the aircraft. Rotation about the x-axis is called roll. Roll rate is denoted $p$, roll angle is denoted $\... 11 Yes, increased maneuverability and redundancy are the main benefits of this layout. Another is a wider possible range of the center of gravity. In the video linked in Federico's comment you can see that the canards reach high negative deflection angles in high-alfa attitudes: This means they will still operate in attached flow when wing and tail are already ... 11 The new 737 MAX has a more advanced pitch control system called maneuvering characteristics augmentation system (MCAS), which automatically adjusts the stabilator trim in case of high thrust and high angle of attack (AOA). This makes it very hard to overcome the down force with elevator input alone (pulling up). In case of a wrong trim adjustment (e.g. due ... 10 A pitching moment is every moment acting around the lateral axis. Since a moment is the combination of a force and a lever arm, the magnitude of the moment depends on the choice of reference point, the point around which the pitching moment is defined. For flight mechanics, it helps to choose the center of gravity for all pitching moments, because then the ... 9 What are the exact meanings of roll, pitch and yaw? It depends somewhat on whether you are speaking from a pilot's point of view or from an engineer's point of view. Your reference to yaw, pitch, and roll ANGLES is indicates you are looking at the situation from an engineering point of view. A pilot would tend to think more in terms of yaw, pitch, and ... 8 Of course it creates a pitching moment! Now we need to define around which reference point this moment should be measured. If the reference point is the center of gravity, it is even equally strong as the pitching moment of the elevator, it only has the opposite direction. If you use the aerodynamic center as the reference point, the moment will be less ... 8 Roll, pitch, and yaw have two different meanings. They can refer to either Euler angles, which describe the attitude (orientation) of an aircraft, or ways that an aircraft can rotate. Euler angles The attitude of an aircraft can be described by three angles: heading, pitch, and bank angle (sometimes called roll angle). The heading$\psi$(psi, sometimes ... 7 The horizontal stabilizer always provides a downward force to balance the forces of lift and weight with the centre of gravity. This also provides stability because if the aircraft pitches down and starts to speed up, the increased airflow over the tail will result in more downward force and cause the nose to rise and the aircraft to slow. As the aircraft ... 7 30 degrees. Boeing aircraft, including the 787, have a Pitch Limit Indicator (PLI) in the flight display that tells the pilot how far the wing's angle of attack (AOA) is from stall. the PLI also is limited to 30 deg of pitch attitude, regardless of AOA. But it depends on aircraft configuration During takeoff climb, there is no single target AOA to ... 7 The reference of pitch is the horizontal. The reference of AoA is the direction of the relative wind. 6 Be careful of confusing manoevrability and agility. The former describes turn performance (min radius, max sustained turn rate etc), while agility describes how quickly it can change manoeuvre state; depends on stability, handling qualities, control power etc. Given this design is based on a legacy version, the large moments of inertia in pitch demand ... 6 The attitude angles are explained in this wikipedia page, but it seems your confusion stems from the fact that they can present a singularity. Each set of unique Euler angles, outside of the gimbal lock state, represent a unique attitude. In the singularity state, however: The angles α, β and γ are uniquely determined except for the singular case that ... 6 1. Aeroelasticity Unlike a tailplane, a delta wing is more rigid due to its much bigger chord and multiple spars, so control reversal due to aeroelasticity isn't a special concern. Big subsonic jetliners typically lock the outer ailerons at high speeds. Concorde featured a similar function for the outer elevon, but only if$V_{MO}$is exceeded by 25 knots ... 5 Roll, pitch and yaw are referred to in one word as the attitude. 5 The pitch of an aircraft relative to the horizon is observed on the Attitude Indicator which also displays roll angle. These are required for IFR flight but not VFR flight here in the US. As such they are found on most but not strictly all aircraft. These are typically gyroscopically based. (source) Here is a basic cutaway of the interior showing where ... 5 There are three principle competing electronic technologies replacing vacuum and electric powered gyros. Higher end systems use ring laser gyros (RLG), and rely on interference pattern changes to detect motion in the axis of the ring laser. Similar, but slightly lower cost are fiber optic gyros (FOG). Lower end systems (including$20 hobby drones) are ...

5

In my checklists, I am required to "set trim for takeoff" in the engine run up. What is the point of this step if that trim setting doesn't hold the proper attitude for not falling out of the sky? A major cause of accidents on take-off and landing is a stall followed by a spin. A wing stalls when it reaches the critical angle of attack, which is much ...

5

How does yaw relate to pitch? There are four forces at play on a single engine aircraft that can cause turning tenancies or Yaw. The main reason a single-engine propeller aircraft yaws left at T/O is due to Asymmetrical Thrust (P-Factor). At high angles of attack the right side of the propeller disc creates more thrust than the left side and this causes ...

5

The Twin Otter isn't unique. Flaps have varying effects on different airplanes. Some pitch up with flaps extended, some pitch down. The pitching moment from flaps isn't just from the nose down moment from the increase in airfoil camber; it includes effects of increased downwash on the tail, which creates a pitch up moment, and to some degree, changes in ...

5

Because airspeed influences the effective angle of attack of your propeller blades. Consider what happens when you move this propeller from a stable cruise condition to a dive. In a dive, the incoming airstream increases, so a propeller with a fixed geometric pitch will have a smaller effective angle of attack. It will then generate less lift and drag, and ...

5

Because the speed brakes are tail mounted, and because they deploy upwards and downwards equally, pitch should not change. The airplane's fly-by-wire system likely dampens any slight pitch changes caused by the buffeting. The only photos I've seen of the speed brakes open are of them fully open, not partially open. So they may open gradually with ...

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